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Thread: what is causing this effect?

  1. #1
    jetcode
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    what is causing this effect?

    4x10 film (color and B/W) same fog pattern in same location on evey neg shot with 360mm Sironar N, no shade, not in direct sunlight. Rotary tube processed film is fine for other lens so it's not the processing and not the film as it appears exactly the same on all sheets color or black and white. This image was shot from the shade.

  2. #2

    Re: what is causing this effect?

    Maybe your lens board is not seated properly and you have a light leak along the side?

    Scott

  3. #3
    alec4444's Avatar
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    Re: what is causing this effect?

    Yikes! Sorta takes the "Elite" out of your Scans.... Sorry, that was irresistible....

    Quote Originally Posted by Scott Kathe View Post
    Maybe your lens board is not seated properly and you have a light leak along the side?

    Scott
    ...which is easy to check. Close the lens, take the back off and point the camera at a bright light source. If you see light, you see problem.

    I don't think it's that, though. Did you notice how the sky seems to appear fine? Is that upper quadrant always ok, or did it just fail on this shot?

    --A

  4. #4
    Kirk Gittings's Avatar
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    Re: what is causing this effect?

    "Did you notice how the sky seems to appear fine? Is that upper quadrant always ok, or did it just fail on this shot?"

    I don't think you can assume that because the texture of the sky may be masking the problem. I would do some tests looking for light leaks withe the lens board, separation of the bellows, fit of the back and fit of the film holder.

    Joe did you process both the color and the b&w in the rotary drum?

    If this was my film, with some development procedures (certain tanks), I would also check for insufficient developer quantity, because in a tank where the film sits upright, the lighter areas might reflect lack of developer and the darker area right below it, increased agitation at the the dev. top level. Does that make any sense? I have seen something like this before and this was the issue.
    Thanks,
    Kirk

    at age 67
    "The woods are lovely, dark and deep,
    But I have promises to keep,
    And miles to go before I sleep,
    And miles to go before I sleep"

  5. #5
    jetcode
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    Re: what is causing this effect?

    Quote Originally Posted by Kirk Gittings View Post
    "Did you notice how the sky seems to appear fine? Is that upper quadrant always ok, or did it just fail on this shot?"

    I don't think you can assume that because the texture of the sky may be masking the problem. I would do some tests looking for light leaks withe the lens board, separation of the bellows, fit of the back and fit of the film holder.

    Joe did you process both the color and the b&w in the rotary drum?

    If this was my film, with some development procedures (certain tanks), I would also check for insufficient developer quantity, because in a tank where the film sits upright, the lighter areas might reflect lack of developer and the darker area right below it, increased agitation at the the dev. top level. Does that make any sense? I have seen something like this before and this was the issue.

    I've processed the same B/W film using a different lens and the effect is not there. The color film was developed elsewhere. I think it is some form of fogging die to light leak at the lens board. This lens is massive and barely fits. The camera is brand new and so far only the 360 has produced these results.

  6. #6
    Kirk Gittings's Avatar
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    Re: what is causing this effect?

    What are your other lens lengths? Sometimes a wide lens shifted extreme will show a light leak problem that a long lens won't and vice versa. Bellows leaks in particular are that way.
    Thanks,
    Kirk

    at age 67
    "The woods are lovely, dark and deep,
    But I have promises to keep,
    And miles to go before I sleep,
    And miles to go before I sleep"

  7. #7
    Resident Heretic Bruce Watson's Avatar
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    Re: what is causing this effect?

    Quote Originally Posted by jetcode View Post
    4x10 film (color and B/W) same fog pattern in same location on evey neg shot with 360mm Sironar N, no shade, not in direct sunlight. Rotary tube processed film is fine for other lens so it's not the processing and not the film as it appears exactly the same on all sheets color or black and white. This image was shot from the shade.
    It's not a light leak. A light leak results in increased exposure, yes? This is decreased exposure. Or more properly decreased density. But you've already ruled out film and processing, so that leaves exposure.

    So I'm thinking that something is blocking (or at least interfering with) light coming from the lens from reaching the film. Could it be a pleat from the bellows up at the lens end -- intruding into the light path just behind the lens? This would be consistent with a really large rear element and the long bellows extension with a long lens -- bellows sagging on one side maybe?

    Bruce Watson

  8. #8
    All metric sizes to 24x30 Ole Tjugen's Avatar
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    Re: what is causing this effect?

    Can you process two films together, taking care to turn one "upside down" compared to the other (i.e. one with the notch top right, one bottom left)? That will show whether the problem is in exposure or processing.

  9. #9
    jetcode
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    Re: what is causing this effect?

    Quote Originally Posted by Kirk Gittings View Post
    What are your other lens lengths? Sometimes a wide lens shifted extreme will show a light leak problem that a long lens won't and vice versa. Bellows leaks in particular are that way.
    I have a 150XL, 240 caltar, 480 ronar

  10. #10
    jetcode
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    Re: what is causing this effect?

    Quote Originally Posted by Bruce Watson View Post
    It's not a light leak. A light leak results in increased exposure, yes? This is decreased exposure. Or more properly decreased density. But you've already ruled out film and processing, so that leaves exposure.

    So I'm thinking that something is blocking (or at least interfering with) light coming from the lens from reaching the film. Could it be a pleat from the bellows up at the lens end -- intruding into the light path just behind the lens? This would be consistent with a really large rear element and the long bellows extension with a long lens -- bellows sagging on one side maybe?
    bruce, what's odd is that the part that appears to be underexposed may actually be properly expose and the rest of the film slightly fogged, it sort of looks that way on the film even though it is not fogged much except at the bar

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